The present invention relates generally to turner apparatus and method for turning flatened elongated articles, such as boards, so that such articles may be inverted several times before they are advanced on a conveyor past such turning apparatus. More specifically, such turning apparatus and method includes a retractable stop means for stopping the elongated article on the conveyor and inverter means including a plurality of turner arms which engage the elongated article and pivot it rearwardly about its rear edge until it falls backward onto the conveyor at a location rearward of the stop position where such article is engaged by the stop means. As a result, the elongated article may be turned over 180.degree. or inverted several times before the stop means is retracted to enable the article to be conveyed forward of such stop means. The turner apparatus and method of the present invention is especially useful for turning boards or panels several times for repeated inspection of both sides of such boards or panels for grading purposes.
Previously board turner apparatus and methods disclosed in U.S. Pat. No. 3,380,570 of Jordan issued Aug. 30, 1968, U.S. Pat. No. 3,426,882 of Korth issued Feb. 11, 1969, U.S Pat. No. 3,552,538 of Triggs et al issued Jan. 5, 1971 and U.S. Pat. No. 3,887,066 of Houtsager issued June 3, 1975 are only capable of single turn inspection because they can only turn over the board through 180.degree. once for inspection of both sides thereof before the board is advanced by a conveyor past the turner apparatus. Thus, these prior board turner apparatus are not capable of turning each board several times for repeated inspections of both sides of the board for more accurate grading, in the manner of the present invention. Furthermore, the turning apparatus employed in such patents is much more complicated, expensive and subject to jamming than that of the present invention. In all of these prior apparatus, the board is pivoted by the turning arms of the inverter means which rotate in the same direction of movement as the conveyor means. As a result, the board is not pivoted about its rear edge to fall backwards onto the conveyor means at a location rearward of a stop position on the conveyor where a retractable stop means engages the leading edge of the board to enable multiple turning of the board, in the manner of the present invention. In addition, none of such prior board turning apparatus employs such an inverter means in combination with a retractable stop means.
The Korth U.S. Pat. No. 3,426,882 and Jordan U.S. Pat. No. 3,380,570 show board turner apparatus including retractable stop means, but the turning arms pivot in the same direction of movement as the conveyor to turn the board so that it falls forward onto the conveyor means at a location forward of the stop position. As a result, multiple turning of the board in the manner of the present invention is impossible. The Triggs et al U.S. Pat. No. 3,552,538 shows a panel turner mechanism which pivots the panel rearwardly by pivoting turning arms. However, there is no retractable stop which engages the leading edge of the panel to stop the panel at a position for multiple turning until the retractable stop is retracted, in the manner of the present invention. Instead, it employs a rear stop arm which engages the trailing edge of the panel when the turning arm raises the panel. Also, a separate support arm is provided above the conveyor against which the panel is moved by the turning arm to keep the panel from falling onto the conveyor at a position rearwardly of the stop arm. Rather than a retractable stop which engages the front edge of the panel, this prior panel turner mechanism employs electrical trip switches to control the cylinder for operating the turning arms when a panel is present, and an electrical circuit for disabeling such trip switches when it is desired to advance the panel.
The Houtsager U.S. Pat. No. 3,887,066 shows an automatic board turner which employs a pair of rotating turner arm wheels which are positioned above the conveyor and rotate in the same direction of movement as the conveyor and engage boards carried by lugs on the conveyor. There is no retractable stop means for stopping advancement of the boards on the conveyor to enable multiple turning of the boards for inspection of both sides of the boad several times, in the manner of the present invention. Thus, the board is not pivoted rearwardly and caused to fall onto the conveyor at a position rearwardly of the stop position where a retractable stop means engages the leading edge of the board, in the manner of the present invention.
Other board inverting mechanisms which do not employ retractable stops or an inverter arm which pivots in an opposite direction to the conveyor to cause the boards to fall backward onto the conveyor at a location rearward of the stop means in the manner of the present invention are U.S. Pat. No. 3,074,530 of Rosenleaf issued Jan. 22, 1963, U.S. Pat. No. 3,247,963 of Fehely issued Aug. 26, 1966 and U.S. Pat. No. 3,306,427 of Spencer issued Feb. 28, 1967.